AB 1769-OF8C ( Scaled For PID ) to AB 1769-IF ( Percent Range ) ?

[Baker in Virginia]

Good Afternoon ,

I have some new machinery that I need to tell another machine what speed I am running. The analog output card that I am sending the speed out of is a 1769-OF8C . It is setup with "Scaled for PID" . The analog input card on the machine that wants to know my speed is a 1769-IF8 . It is setup for "Percent Range". would that make a difference ? It seems like they would need to be the same , don't you think ?

The analog output card is coming from, I believe , a PowerFlex 525 Add-On Instruction . The analog output is coming from M1055.Speed_Reference *16383.0 in a CPT , and the Dest is Local:6:O.Ch0Data.

Thanks again ,

 

[ASF]

Ultimately, how they are set up makes no difference, as long as your scaling in each PLC is set up to account for it.

Think of it this way.

PLC1 has a value inside of it that varies from 0-100 with respect to speed.
That signal needs to get turned into a 4-20mA signal on your 1769-OF8C.

PLC2 needs to read 4-20mA on it's 1769-IF8, where 4mA means the other PLC has a speed of 0, and 20mA means it has a speed of 100.
So, the 4-20mA signal needs to be converted to 0-100 inside PLC2.

Scaled for PID and Percent Range are different, obviously, and I don't off the top of my head know what the correct values are - so for the purposes of this example, let's pretend I'm using a 1756 or 1734 series analog card, where I can define the scaling myself.

Let's say I scale my analog output card 4000-20000. Nice and easy: 4000 = 4mA, 20000=20mA. Now I have to do some scaling to convert 0-100 into 4000-20000.

At the other end, I scale my analog input card 0-10000. 4mA=0, 20mA=10000. So at this end, I scale my analog input to convert 0-10000 into 0-100.

At the end of all this, you get:
PLC1 0-100
>>PLC1 4000-20000
>>PLC1 4-20mA
>>PLC2 4-20mA
>>PLC2 0-10000
>>PLC2 0-100

Job done!

tl;dr - it doesn't matter what format your analog I/O uses, you just have to scale it accordingly at both ends.